1. Field of the Invention
The invention is related to a fixed voltage generating circuit, and more particularly, to a fixed voltage generating circuit fabricated using a GaAs (GALLIUM ARSENIDE) process.
2. Description of the Prior Art
An RF power amplifier fabricated using a GaAs process has good performance and high efficiency, specifically, the RF power amplifier is less prone to signal distortion and has a lower noise to signal ratio, lower power consumption, higher gain, and smaller size. Thus the RF power amplifier gains advantages of shrinking sizes, increasing efficiency, and lowering power consumption of electronic components, and is suitable for use in mobile phones and various of communication devices.
In order that the RF power amplifier fabricated using a GaAs process can function normally under a wide input voltage range, a fixed voltage generated by a fixed voltage generating circuit is provided for operations of the RF power amplifier to ensure the RF power amplifier can function normally.
However the fixed voltage generating circuit is usually fabricated using a CMOS (complementary metal-oxide-semiconductor) process, which includes PMOS (P-type metal-oxide-semiconductor) that is not adoptable in GaAs process. Thus the fixed voltage generating circuit cannot be integrated and fabricated in the same GaAs process when fabricating the RF power amplifier. Instead, an additional CMOS process is needed for fabricating the fixed voltage generating circuit to provide the fixed voltage to the RF power amplifier, thereby increasing area consumption and lowering integration level of related circuit blocks.